This invention relates to apparatus for producing shrink-sealable plastic caps for bottles and the like. The apparatus may be used to produce caps for subsequent use, or provided with means for placing the caps immediately onto the bottles. After the cap has been placed over the mouth and neck of a bottle, it is shrunken to fit tightly, thereby forming a tamper-proof seal. The apparatus may be adapted so as to produce the caps either from plastic tubing and metal foil containing strip, or from precut bands of such tubing, or from precut discs of metal-foil or metal-foil laminates, respectively.
The use of caps made of shrinkable plastic film for sealing bottles, for example, wine bottles, as well as other containers sought to be made tamper-proof is well known. The cap may be made of any suitable transparent or opaque plastic film which can shrunk to form a tight fitting seal around the mouth or neck of the container to be capped. Although wet films whch shrink on drying are known, the preferred materials are commercially available heat-shrinkable films of a polyolefin or polyvinylchloride (PVC).
Machines for placing caps of shrinkable film over bottles are also known. Conventional, such machines include a conveyor which carries the bottles to the capping station. There either the machine places a heat-shrinkable cap over the mouth and neck of the bottle or the cap is placed thereon manually, after which the conveyor carries the bottle through a tunnel-heater which causes the film to shrink tightly around the neck of the bottle. However, machines which are capable of either manufacturing caps or of placing caps onto bottles at speeds sufficiently high to keep up with modern high speed bottle filling machinery, where speeds of up to 150 bottles per minute are desirable, are not available. One reason such high bottle capping speeds have not been attained by the prior art is that the caps, which are stacked for purposes of storage and feeding, tend to stick together, and no mechanical system is believed to have been devised that is capable of placing caps fed from a stack onto bottles at such high rates.